This invention is related to a process for separating the gaseous phase contained in a flow stream having solid, liquid, and gaseous components. More specifically, the present invention is related to the continuous separation of the gaseous phase from a hydrocarbon liquid containing carbonaceous particulates and gases.
In conventional coal liquefaction processes, a light-hydrocarbon liquid stream containing gases and fine solid particles is withdrawn from the high temperature hydrogenation reaction step. The gases are separated from the liquid, purified, and recycled to the reaction step. As to the particulate-liquid slurry, this is subjected to further processing steps.
In designing the phase separators for such gas-liquid-solid mixtures, it has been conventional to use the following equation: ##EQU1## Where: U=vapor exit velocity, ft/sec
.rho.e=liquid density PA1 .rho.g=vapor density
In order to provide a maximum gas exit velocity without entrainment of liquid droplets, K has been known to be limited to about 0.01. In addition, it is also known to place the vapor exit at a minimum distance of about 3 feet from the liquid surface to allow for vapor disengagement.
It has been found that the use of such conventional design criteria for a phase separator handling hot coal-derived liquids is undesirable, since under these conditions the fine particulates comprising unreacted coal and ash settle on the interior surface. These settled particulates, at elevated temperatures of 700.degree.-900.degree. F. and with a deficiency of hydrogen, result in the formation of tough coke deposits in the lower portions of the separator. These deposits cause plugging and present a severe obstacle to the efficient and economical operation of coal liquefaction and conversion processes.
It has been discovered that by varying the processing conditions under which the phase separator is operated, the problems of coking and plugging may be avoided or entirely eliminated.